Well tools



Sept. 28, 1965 Filed. Aug. 19, 1963 J. T. ROARK 3,208,788"

WELL TOOLS 2 Sheets-Sheet l Fig.2

INVENTOR James T. Roork Fig.\ /5 MW M ATTORNEYS Sept. 28, 1965 FiledAug. 19, 1963 J. ROARK 3,208,788

WELL TOOLS 2 Sheets-Sheet 2 INVENTOR James T. Roork United States Patent3,208,788 WELL TOOLS James T. Roark, Houston, Tex., assignor to OtisEngineering Corporation, Dallas, Tern, a corporation of Delaware FiledAug. 19, 1963, Ser. No. 302,860 14 Claims. (Cl. 294-86.15)

This invention relates to well tools and more particularly to a tool forretrieving objects, such as tubing and the like from a well.

An object of this invention is to provide a new and improved well toolwhich is lowerable in a well to engage and grip an object in the wellfor removing the object upwardly from the well.

Another object is to provide a retrieving tool having gripping means forengaging an object, such as the upper end of a tubing in a well, whichgripping means are forced into gripping engagement with the object upondownward movement of the retrieving tool relative to the tubing afterthe engagement of the retrieving tool therewith and which are alsoforced and held in gripping engagement with the tubing upon an upwardforce there-after being applied to the retrieving tool.

Still another object is to provide a retrieving tool lowerable into thewell by means of a string of pipe and operable to grip and hold theobject which is to be retrieved from the well without the necessity ofimparting any rotational movement to the string of pipe by which theretrieving tool is lowered into the well.

A further object is to provide a retrieving tool having hydraulicallyoperated gripping means for engaging and holding an object to beretrieved from a well.

A still further object is to provide a retrieving tool having pump meansand an operator piston movable by fluid pumped by the pump means formoving the gripping means into gripping engagement with an object.

A still further object is to provide a retrieving tool having pump meansfor operating the operator piston which causes power fluid to be appliedto the operable piston upon downward movement of the retrieving toolrelative to the pump piston upon the engagement of the pump piston withan object to be retrieved.

Another object is to provide a retrieving tool having a pair oftelescoped pistons, one of which is provided with a gripping meansmovable inwardly to engage an object telescoped into the lower end ofthe retrieving tool and the other having means engageable with the upperend of the object whereby downward movement of the retrieving toolrelative to the pump piston causes the pump piston to supply fluid underpressure to the operator piston and causes downward movement of theoperator piston and engagement of the gripping means thereof with theobject to be retrieved.

Additional objects and advantages of the invention will be readilyapparent from the reading of the following description of a deviceconstructed in accordance with the invention, and reference to theaccompanying drawings thereof, wherein:

FIGURE 1 is a vertical partly sectional View of the upper portions ofthe retrieving tool showing it connected to the lower 'end of a stringof pipe by means of which it is lowered into the well and showing thepump and operator pistons in their normal positions;

FIGURE 2 is a view similar to FIGURE 1, being a continuation thereof,and showing the lower portions of the well tool telescoped over theupper end of a tubing which is to be retrieved from the well;

FIGURE 3 is a vertical partly sectional view showing the pistons intheir operative positions during the removal of the string of tubingfrom the well;

FIGURE 4 is a view similar to FIGURE 3, being a continuation thereof,showing the lower portions of the Well tool with the gripping meansthereof in gripping engagement with the tubing being removed from thewell; and

FIGURE 5 is a fragmentary vertical partly sectional view showing thegripping means of the retrieving tool.

Referring now particularly to the drawings, the retrieving tool It)embodying the invention includes a tubular body or mandrel 11 whose topsection 12 is threadable on the lower end of string of pipe by means ofwhich the retrieving tool is lowered into the well. The mandrel has anintermediate tubular or barrel section 13 whose upper end portion isthreaded on the bottom portion of the top section, and a cam or bottomsection 15 whose upper end portion is threaded into the loWer endportion of the barrel section.

The top mandrel section has an internal annular de pendent portion 17 ofdecreased external diameter which forms with the barrel section an upperpiston chamber 18 in which is slidable the annular pump piston 19. Thepump piston has an O-ring 20 received in a suitable internal annularrecess thereof which seals between the piston and the dependent portion17 of the top mandrel section and an O-ring 21 disposed in suitableexternal annular recess thereof which seals between the barrel mandrelsection and the piston pump below a lateral portion 22 of a bypass flowpassage 23 of the pump piston. The longitudinal portion 24 of the flowpassage 23 opens downwardly through the orifice 25 of a spring retainer26 threaded in the lower end of the longitudinal portion. The spring 27disposed in the longitudinal portion of the flow passage biases a ballcheck valve 28 against an annular seat 29 of the piston, its lower endbearing against the retainer and its upper end against the ball checkvalve.

The ball check valve at all times prevents upward flow of liquid throughthe bypass flow passage 23, and prevents downward flow therethroughuntil the pressure within the upper chamber 18 above the pump piston hasincreased to a value sutliciently great to overcome the force exerted bythe spring 27 on the ball valve.

Liquid, such as oil, is introducible into the top portion 18a of theupper chamber 18 above the pump piston through an inlet passage 30 ofthe top mandrel section whose upper lateral portion 32 is closable by asuitable plug 33. An O-ring 35 disposed in an external annular recess ofthe top mandrel section seals between the barrel mandrel section and thetop mandrel section so that when the plug 33 closes the inlet passage30, liquid can escape from the upper chamber above the pump piston onlythrough the bypass flow passage 23 of the pump piston.

Upward movement of the pump piston in the upper chamber is limited bythe engagement of its top annular end surface 37 with the annulardownwardly facing annular stop shoulder 38 of the top mandrel sectionwhile its downward movement in the upper chamber is limited by theengagement of its annular bottom end surface 39 with the internalannular shoulder 40 of the barrel mandrel section which defines thelower end of the upper piston chamber.

The pump piston 19 includes a dependent sleeve 42 whose reduced upperend portion 43 is threaded in the lower end portion of the pump piston.An O-ring 44 disposed in an annular external recess of the pump pistonseals between the piston and the sleeve 42. The external surface 45 ofthe dependent portion 17 is of a smaller diameter than the externalsurface 46 of the pump piston sleeve 42 so that the width of bottomportion 18b of the upper chamber below the lower end of the pump pistondefined by the external surface 46 and the internal surface 47 of thebarrel mandrel section, as pump piston moves upwardly in the chamber 18,is smaller than the width of the top portion 18a above the O-rings 20and 21 of the pump piston. The volume of liquid displaced from above thepump piston as it moves upwardly thus is greater than the volume oflower portion 18b of the chamber and the liquid thus pumped by the pumppiston is therefore forced into the upper end of a lower annular pistonchamber 48. The lower piston chamber 48 has a width-smaller than that ofthe lower portion 18b of the upper chamber 18 being defined by theexternal surface 46 of the sleeve 42 and the internal surface 49 of thebarrel mandrel section below the shoulder 40 thereof which is of smallerdiameter than the internal surface 47 defining the upper chamber.

The operator piston 50 is slidably disposed in the lower chamber and hasO-rings 51 and 52 disposed in suitable internal and external recessesthereof which engage the surfaces 49 and 46 of the barrel mandrelsection and the sleeve 42, respectively. The operator piston has aplurality of dependent resilient collet fingers 55 whose lower ends areprovided with inner serrations or teeth 56 and with external bosses 57.The bosses have outer cam surfaces inclined downwardly and inwardlywhich are engageable with the internal downwardly and inwardly extendingor beveled cam surface 59 of the bottom mandrel section 15. The externalbosses of the collet fingers are receivable in the lower enlargedinternal portion 60 of the bore or passage of the barrel mandrel section13 above the bottom mandrel section which permits the collet fingers toassume their inherent inoperative outer positions illustrated in FIGURES2 and 5.

The pump piston sleeve 42 has an external annular flange 62 whichprovides an upwardly facing external shoulder 63 engageable with thedownwardly facing internal annular shoulder 64 of the operator piston tolimit downward movement of the operator piston relative thereto. Thebottom mandrel section has an upwardly and inwardly inclined cam orbeveled surface 65 which is engageable with the upper end of the object,such as the tubing 66, which is to be removed from the well.

In use, when an object is to be retrieved or removed from a well, forexample the tubing 66 whose upper end portion may have broken off, theoperator piston 50 of the retrieving tool is moved to its uppermostposition in the mandrel wherein its annular top end surface engages theannular bottom end surface of the pump piston 19 so that the externalbosses 57 of the collet fingers are in the enlarged portion 60 of thebore of the barrel mandrel section and the collet fingers are in theirouter inoperative positions in the mandrel illustrated in FIGURES 2 and5. An incompressible fluid, such as oil, is then intro duced into thetop portion 18a of the upper pump piston chamber 18 through the inletpassage of the mandrel to fill the upper chamber portion 18a above thepump piston 19 which is then in its lowermost position in the mandrel.The plug 33 is then threaded in the enlarged portion of the lateralportion 32 of the inlet passage and closes the inlet passage.

The check valve 28 now prevents flow of the oil from the upper chamberportion 18a through the bypass flow passage 23 to the lower chamberportion 18b due to the force exerted thereon by the spring 27 and theoperator piston is held against downward movement in the mandrel sinceany downward movement thereof tends to create a vacuum in the lowerchamber portion 18b. In addition, the collet fingers 55 tend to hold theoperator piston in the upper position illustrated in FIGURE 1 due to theengagement of the cam surfaces 58 thereof with the cam surface 59 of themandrel and the resilient force with which the collet fingers resistinward flexing or movement. The operator piston is thus held in itsuppermost position against any accidental downward movement in themandrel and the collet fingers remain in 4 their outer inoperativepositions during lowering of the retrieving tool into the well.

The retrieving tool is then lowered into the well on a string of pipeuntil the lower end of the mandrel telescopes over the upper end of theobject which is to be retrieved, such as the upper end of the tubing 66.The cam surface or shoulder 65 of the bottom mandrel section guides thedownward movement of the mandrel over the upperend of the tubing.

As the retrieving tool telescopes over the upper end portion of thetubing and the collet fingers move downwardly therea'bout, their teethor serrations 56 do not engage the outer surface of the tubing since thelower ends of the collet fingers are now in their outer inoperativepositions. The retrieving tool is moved downwardly over the upper endportion of the tubing until the'top end surface of the tubing engagesthe bottom surface 68 of the pump piston sleeve 42 which is beveledinwardly and upwardly to help center the retrieving tool on the tubingas it is lowered thereon. Once the pump piston sleeve engages the upperend of the tubing further downward movement of the pump piston isarrested.

A downward force then imposed on the mandrel 11 of the retrieving toolby means of the string of pipe then causes further downward movement ofthe mandrel relative to the pump piston and over the upper end portionof the tubing and the incompressible liquid in the upper portion 18a ofthe pump piston chamber 18 is forced or pumped downwardly through thebypass flow passage 23 into the lower. portion 18b and thence into theupper end of the operator piston chamber 48, the check valve 28 movingdownwardly against the resistance of the spring 27 and from its sealingengagement with the seat 29 to permit such flow of fluid in the chamber18 past the piston 19. Since the rate of decrease of volume of the upperportion 18a of the chamber is greater than the rate of increase of thevolume of the lower portion 1817, the liquid thus pumped into the upperend of the operator piston chamber moves the operator piston downwardlyin the mandrel.

Downward movement of the operator piston in the mandrel causes the lowerends of the collet fingers to be moved inwardly due to the cammingengagement of their cam surfaces 58 with the cam surface 59 of themandrel cam section 15 and the teeth or serrations 56 of the colletfingers to engage and dig into the external surfaces of the tubing.

When further downward movement of the retrieving tool is arrested as thelower ends of the collet fingers reach the limit of their inwardmovement after their teeth have dug into the tubing, .an upward force isimparted to the string of .pipe at the surface of the well and theupward force applied thereby to the mandrel will tend to move themandrel cam surface 59 upwardly relative to the cam surface 58 of thecollet fingers and thus will tend to move the lower ends of the colletfingers inwardly and, at the same time, will tend to move the colletfingers, and therefore the tubing 62 held thereby, upwardly with themandrel. It will be apparent that the greater the force necessary tomove the tubing upwardly, the greater will be the force with which theserrations or teeth of the collet fingers are held in grippingengagement with the tubing so that the tubing will be thus held againstdownward movement relative to the mandrel and will be raised with theretrieving tool as the string of pipe is raised upwardly to the surface.

It will be apparent that once the operator piston 50 is moved downwardlyand the collet teeth have engaged the tubing, the retrieving tool cannotbe disengaged from the tubing since the incompressible liquid in thelower chamber 48 above the operator piston and in the lower portion 18bof the upper chamber 18 below the operator piston 19, cannot flow backinto the upper portion 18a of the upper chamber due to the check valve28 which prevents upward flow of fluid through the bypass flow passage23.

When the retrieving tool and the tubing so engaged thereby is removedfrom the well at the surface, the retrieving tool can be easilydisengaged from the tubing by unscrewing the mandrel sections from oneanother.

It will now be seen that a new and improved retrieving tool has beenillustrated and described which has gripping means which inherently tendto remain in outer inoperative positions and which are movable intogripping engagement with an object to be removed from a well by ahydraulic means which includes the pump and operator pistons 19 and 50.

It will further be seen that the mandrel and the gripping means havecoengageable means, such as the cam surfaces 58 and 59, which cause thegripper means to move inwardly to grip an object disposed therebetweenupon relative longitudinal movement of the operator gripping means andthe mandrel.

It will further be seen that the new and improved retrieving tool doesnot require any rotary movement of the means, such as the string ofpipe, by which it is lowered into the well to cause the engagement ofits gripping means with the object to be retrieved and that the forcewith which the gripping means engage and hold the object increases asthe force with which such object resists removal from the well.

It will further be seen that the retrieving tool including ahydraulically activated gripping means movable in a tubular mandrel forengaging an object receivable in the mandrel and a pump means in themandrel for supplying liquid under pressure to move the gripping meansrelative to the mandrel and into engagement with the object, the pumpmeans being engageable with such object whereby the movement of themandrel relative to the pump means then causes the pump means to supplyliquid under pressure to the gripping means.

It will be further seen that while the bypass flow passage 23 connectingthe upper and lower portions 18a and 18b of the pump piston chamber isprovided in the pump piston for compactness and ease of manufacture, itmay be provided in the barrel mandrel section or by an external conduitconnecting upper and lower ends of the pump piston chamber.

The foregoing description of the invention is explanatory only, andchanges in the details of the construction illustrated may be made bythose skilled in the art, within the scope of the appended claims,without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A retrieving tool including: a tubular member; hydraulically actuatedgripping means movable in said tubular member for engaging an objectreceivable in said tubular member; and pump means carried by saidtubular member for supplying fluid under pressure to said gripping meansto move said gripping means relative to said tubular member and intoengagement with said object in said tubular member, said pump meansbeing engageable with a surface in said tubular member to limit movementof said pump means relative to said tubular member, whereby movement ofsaid tubular member relative to the object and to said pump means aftersaid pump means has been engaged by said surface causes liquid underpressure to be supplied to said gripping means to move said grippingmeans into gripping engagement with the object.

2. A retrieving tool including: a tubular member having a pair of pistonchambers; a pump piston in one of said chambers and an operator pistonin the other of said chambers; gripping means operatively connected tosaid operator piston, said gripping means and said tubular member havingco-engageable means for moving said gripping means from an inoperativeposition to an operative gripping position upon relative movementbetween said tubular member and said operator piston; and meansengageable with an object to be retrieved by said retrieving tool forholding said pump piston against movement while said tubular member ismoved relative to the object, said retrieving tool having passage meanspermitting flow of fluid from said one chamber into said other chamberfor moving said operator piston relative to said tubular member uponrelative longitudinal movement between said pump piston and said tubularmember.

3. A retrieving tool including: a tubular member having a pair of pistonchambers; a pump piston in one of said chambers and an operator pistonin the other of said chambers; gripping means operatively connected withsaid operator piston, said gripping means and said tubular member havingco-engageable means for moving said gripping means from an inoperativeposition to an operative gripping position upon relative movementbetween said tubular member and said operator piston; and meansengageable with an object to be retrieved by said retrieving tool forholding said pump piston against movement while said tubular member ismoved relative to the object, said retrieving tool having passage meanspermitting flow of fluid from said one chamber into said other chamberfor moving said operator piston relative to said tubular member uponrelative longitudinal movement between said pump piston and said tubularmember; and valve means preventing flow of fluid from said other chamberinto said one chamber.

4. A retrieving tool including: a tubular member having a longitudinalpassage therethrough and a pair of longitudinally extending pistonchambers; a pump piston in one of said chambers for pumping fluid fromsaid one of said chambers into the other of said chambers uponlongitudinal movement in one direction of said pump piston in said oneof said chambers; an operator piston in the other of said chambers andmovable longitudinally of said tubular member in a second directionopposite said one direction by fluid pumped into said other of saidchambers by said pump piston; and gripping means in said tubular memberoperatively connected with said operator piston, said gripping means andsaid tubular member having co-engageable means for moving said grippingmeans from an inoperative position to an operative gripping positionupon relative movement between said tubular member and said operatorpiston, said pump piston having means engageable with an object to beretrieved by said retrieving tool for holding said pump piston againstmovement while said tubular member is moved in said second direction.

5. A retrieving tool including: a tubular member having a longitudinalpassage therethrough and a pair of longitudinally extending pistonchambers; a pump piston in one of said chambers for pumping fluid fromsaid one of said chambers into the other of said chambers uponlongitudinal movement in one direction of said pump piston in said oneof said chambers; an operator piston in the other of said chambersmovable longitudinally of said tubular member in a second directionopposite said one direction by fluid pumped into said other of saidchambers by said pump piston; gripping means operatively connected withsaid operator piston, said gripping means and said tubular member havingco-engageable means for moving said gripping means from inoperativeposition to an operative gripping position on relative movement betweensaid tubular member and said operator piston, said pump piston havingmeans engageable with an object to be retrieved by said retrieving toolfor holding said pump piston against movement while said tubular memberis moved in said second direction, said well tool having passage meanspermitting flow of fluid pumped from said one chamber by said pumppiston into said other chamber; and check valve means for preventingflow of fluid through said passage from said other chamber into said onechamber.

6. A retrieving tool including: a tubular mandrel having means providingan annular first piston chamber; an annular pump piston longitudinallymovable in said chamher and having means providing with said mandrel asecond annular chamber having fluid communication with said first pistonchamber; an annular operator piston longitudinally movable in saidsecond chamber; gripping means disposed in said mandrel and operativelyconnected with said operator piston for engaging an object extendinginto said mandrel, said gripping means and said mandrel havingco-engageable means for moving said gripping means inwardly to engagesaid object in said mandrel upon longitudinal movement of said operatorpiston relative to said mandrel, said tool having passage means fortransmitting fluid from said first chamber to said second chamber inresponse to movement of said pump piston for moving said operator pistonlongitudinally to move said gripping means to engaging position.

7. A retrieving tool including: a tubular mandrel having upper and lowerends and having means providing an annular upper piston chamber; anannular pump piston longitudinally movable in said chamber and havingmeans providing with said mandrel a lower annular chamber whose upperend is in communication with the lower end of said upper piston chamber;an annular operator piston longitudinally movable in said lower chamber;gripping means disposed in said mandrel and operatively connected withsaid operator piston for engaging an object extending upwardly into saidmandrel, said gripping means and said mandrel having co-engageable meansfor moving said gripping means inwardly to engage said object receivedin said mandrel upon downward movement of said operator piston relativeto said mandrel, said tool having passage means for transmitting fluidfrom the upper end of said upper chamber to the upper end of said lowerchamber in response to movement of said pump piston for moving saidoperator piston downwardly, said pump piston having means engageablewith a surface of said object in said mandrel for limiting downwardmovement of said pump piston while said mandrel is moved downwardly.

8. A retrieving tool including: a tubular mandrel having upper and lowerends having means providing an annular upper piston chamber; an annularpump piston longitudinally movable in said chamber and having meansproviding with said mandrel a lower annular chamber whose upper end isin communication with the lower end of said upper piston chamber; anannular operator piston longitudinally movable in said lower chamber;and gripping means disposed in said mandrel and operatively connectedwith said operator piston for engaging an object extending upwardly intosaid mandrel, said gripping means and said mandrel having co-engageablemeans for moving said gripping means inwardly to engage said objectreceived in said mandrel upon downward movement of said operator pistonrelative to said mandrel, said tool having passage means fortransmitting fluid from the upper end of said upper chamber to the upperend of said lower chamber for moving said operator piston downwardly,said pump piston having means engageable with a surface of said objectreceived in the lower end portion of said mandrel, whereby downwardmovement of said mandrel relative to said object moves said pistonrelatively upwardly in said upper chamber to force fluid from said upperchamber to said lower chamber; said tool having valve means preventingflow of fluid from said lower chamber into said upper portion of saidupper chamber through said passage means.

9. A retrieving tool including: a tubular mandrel adapted to be operatedwith its longitudinal axis disposed vertically and having meansproviding an annular upper piston chamber; an annular pump pistonlongitudinally movable in said chamber and having means providing withsaid mandrel a lower annular chamber whose upper end is in communicationwith the lower end of said upper piston chamber; an annular operatorpiston longitudinally movable in said lower chamber; and gripping meansdisposed in said mandrel and operatively connected with said operatorpiston for engaging an object extending upwardly into said mandrel, saidgripping means and said mandrel hav- 8. ing co-engageable means formoving'said gripping means inwardly to engage said object received insaid mandrel upon downward movement of said operator piston relative tosaid mandrel, said tool having passage means for transmitting fluid fromthe upper end of said upper chamber to the upper end of said lowerchamber in response to movement of said pump piston in said upperchamber for moving said operator piston downwardly to move said grippingmeans to engaging position, said gripping means comprising a pluralityof collet members extending downwardly from said operator piston, saidco-engageable means comprising an internal downwardly and inwardlybeveled cam surface of said mandrel and downwardly and inwardly inclinedouter cam surfaces of said collet members whereby when said colletmembers are in engagement with said object received in the lower end ofsaid mandrel an upward force imparted to said mandrel tends to move saidcollet members inwardly and into engagement'with the object.

10. A retrieving tool including: a tubular mandrel adapted for operationwith, its longitudinal axis in a vertical plane and having meansproviding an annular upper piston chamber; an annular pump pistonlongitudinally movable in said chamber and having means providing withsaid mandrel a lower annular chamber whose upper end is in communicationwith the lower end of said upper piston chamber; an annular operatorpiston longitudinally movable in said lower chamber; and gripping meansdisposed in said mandrel and operatively connected to said operatorpiston for engaging anvobject extending upwardly into said mandrel, saidgripping means and said mandrel having co-engageable means for movingsaid gripping means inwardly to engage said object received in saidmandrel upon downward movement of said operator piston relative to saidmandrel, said pump piston having a bypass flow passage communicating theupper end portion of said upper piston chamber above said pump pistonwith the lower end portion of said piston chamber for conducting fluidfrom said upper chamber to said lower chamber in response to relativeupward movement of said pump piston in said upper chamber for movingsaid operator piston downwardly.

11. A retrieving tool including: a tubular mandrel adapted to beoperated with its longitudinal axis disposed vertically and having meansproviding an annular upper piston chamber; an annular pump pistonlongitudinally movable in said chamber and having means providing withsaid mandrel a lower annular chamber whose upper end is in communicationwith the lower end of said upper piston chamber; an annular operatorpiston longitudinally movable in said lower chamber; gripping meansdisposed in said mandrel and operatively connected with said operatorpiston, for engaging an object extending upwardly into said mandrel,said gripping means and said mandrel having co-engageable means formoving said gripping means inwardly to engage said object received insaid mandrel upon downward movement of said operator piston relative tosaid mandrel, said pump piston having a bypass flow passagecommunicating the upper end portion of said upper piston chamber abovesaid pump piston with the lower end portion of said piston chamber forconducting fluid from said upper chamber to said lower chamber inresponse to upward movement of said pump piston in said upper pistonchamber for moving said operator piston downwardly in said lowerchamber; and valve means for preventing flow of fluids from said lowerchamber into said upper end portion of said upper chamber through saidbypass flow passage.

12. A retrieving tool including: a tubular mandrel adapted to beoperated with its longitudinal axis disposed vertically and having meansproviding an annular upper piston chamber; an annular pump pistonlongitudinally movable in said upper chamber and having means providingwith said mandrel a lower annular chamber whose upper end is incommunication with the lower end of said upper piston chamber; anannular operator piston longitudinally movable in said lower chamber;and gripping means disposed in said mandrel and operatively connectedwith said operator piston for engaging an object extending upwardly intosaid mandrel, said gripping means and said mandrel having co-engageablemeans for moving said gripping means inwardly to engage said objectreceived in said mandrel upon downward movement of said operator pistonrelative to said mandrel, said pump piston having a bypass flow passagecommunicating the upper end portion of said upper piston chamber abovesaid pump piston with the lower end portion of said piston chamber forconducting fluid from said upper chamber to said lower chamber inresponse to upward movement of said pump piston in said upper pistonchamber for moving said operator piston downwardly in said lowerchamber, said pump piston having means engageable with a surface of saidobject received in the lower end portion of said mandrel for limitingdownward movement of said pump piston relative to said object while saidmandrel is moved downwardly.

13. A retrieving tool including: a tubular mandrel adapted to beoperated with its longitudinal axis disposed vertically and having meansproviding an annular upper piston chamber; an annular pump pistonlongitudinally movable in said upper chamber and having means providingwith said mandrel a lower annular chamber whose upper end is incommunication with the lower end of said upper piston chamber; anannular operator piston longi tudinally movable in said lower chamber;and gripping means disposed in said mandrel and operatively connectedwith said operator piston for engaging an object extending upwardly intosaid mandrel, said gripping means and said mandrel having co-engageablemeans for moving said gripping means inwardly to engage said objectreceived in said mandrel upon downward movement of said operator pistonrelative to said mandrel, said pump piston hav ing a bypass flow passagecommunicating the upper end portion of said upper piston chamber abovesaid pump piston with the lower end portion of said piston chamber forconducting fluid from said upper chamber to said lower chamber inresponse to upward movement of said pump piston in said upper pistonchamber for moving said operator piston downwardly in said lowerchamber, said tool having valve means for preventing flow of fluid fromsaid lower chamber into said upper portion of said upper chamber throughsaid passage means.

14. A retrieving tool including: a tubular mandrel adapted to beoperated with its longitudinal axis disposed vertically and having meansproviding an annular upper piston chamber; an annular pump pistonlongitudinally movable in said upper chamber and having means providingwith said mandrel a lower annular chamber whose upper end is incommunication with the lower end of said upper piston chamber; anannular operator piston longitudinally moveable in said lower chamber;gripping means disposed in said mandrel and operatively connected withsaid operator piston for engaging an object extending upwardly into saidmandrel, said gripping means and said mandrel having co-engageable meansfor moving said gripping means inwardly to engage said object receivedin said mandrel upon downward movement of said operator piston relativeto said mandrel, said pump piston having a bypass flow passagecommunicating the upper end portion of said upper piston chamber abovesaid pump piston with the lower end portion of said piston chamber forconducting fluid from said upper chamber to said lower chamber inresponse to upward movement of said pump piston in said upper chamberfor moving said operator piston downwardly in said lower chamber to movesaid gripping means to engaging position; and valve means for preventingflow of fluids from said lower chamber into said upper chamber throughsaid bypass flow passage.

References Cited by the Examiner UNITED STATES PATENTS 5/30 Fischbach294-8615 SAMUEL F. COLEMAN, Primary Examiner.

ERNEST A. FALLER, Examiner.

1. A RETRIEVING TOOL INCLUDING: A TUBULAR MEMBER; HYDRAULICALLY ACTUATEDGRIPPING MEANS MOVABLE IN SAID TUBULAR MEMBER FOR ENGAGING AN OBJECTRECEIVABLE IN SAID TUBULAR MEMBER; AND PUMP MEANS CARRIUED BY SAIDTUBULAR MEMBER FOR SUPPLYING FLUID UNDER PRESSURE TO SAID GRIPPING MEANSTO MOVE SAID GRIPPING MEANS RELATIVE TO SAID TUBULAR MEMBER AND INTOENGAGEMENT WITH SAID OBJECT IN SAID TUBULAR MEMBER, SAID PUMP MEANSBEING ENGAGEABLE WITH A SURFACE IN SAID TUBULAR MEMBER TO LIMIT MOVEMENTOF SIAD PUMP MEANS RELATIVE TO SAI D TUBULAR MEMBER, WHEREBY MOVEMENT OFSAID TUBULAR MEMBER RELATIVE TO THE OBJECT AND TO SAID PUMP MEANS AFTERSAID PUMP MEANS HAS BEEN ENGAGED BY SAID SURFACE CAUSES LIQUID UNDERPRESSURE TO BE SUPPLIED TO SAID GRIPPING MEANS TO MOVE SAID GRIPPINGMEANS INTO GRIPPING ENGAGEMENT WITH THE OBJECT.